This multifaceted project aims at understanding the physical basis for various cell activities that involve structural changes in supramolecular biomolecular complexes. Recent emphasis has been on mechanisms involved in biological vesicle formation, but several projects involving tubulin polymers also were carried out. A thermodynamic analysis of protein coat assembly in receptor mediated endocytosis was used to establish relationships between clathrin basket assembly and parameters such as clathrin interarm association energies, intrinsic triskelion curvature, and the bending rigidity of the triskelions. Fluorescence recovery after photobleaching (FRAP) was employed to study temperature induced structural changes in bilayers formed from total lipid extracts of E.coli cell membranes, the purpose being to understand phase changes that occur when cellular lipids are maintained at temperatures near their growth temperatures. A series of physical analyses involving dynamic light scattering and small angle neutron scattering were undertaken to determine parameters of microtubule structure, particularly as they are affected by a variety of antimitotic drugs; in particular, protocols were devised for using quasielastic light scattering to study the induction of tubulin rings by marine natural peptides, such as cryptophycin and dolastatin, which are being investigated as potential new chemotherapeutic agents. - biological vesicles, endocytosis, clathrin, FRAP, dynamic light scattering, SANS, tubulin